S1 ACT11.2D Interior Angles (On the Same Side of Transversal) Theorem

In the applet below, a TRANSVERSAL intersects 2 PARALLEL LINES. When this happens, there are 2 pairs of INTERIOR ANGLES (ON THE SAME SIDE OF TRANSVERSAL) that are formed. Interact with the applet below for a few minutes, then answer the questions that immediately follow.
Directions & Questions: 1) Complete the following statement: If a transversal intersects 2 ________________ ______________, then same-side interior angles are _____________________. 2) If the gray angle above measures 120 degrees, what would the measure of its same-side interior angle be? 3) As you moved the slider, what transformation(s) took place?